U.S. patent application number 13/133789 was filed with the patent office on 2011-10-06 for apparatus for treating a medical liquid, and method for checking the leaktightness of the apparatus.
Invention is credited to Daniel Gerlach, Ralf Muller, Peter Scheunert.
Application Number | 20110239742 13/133789 |
Document ID | / |
Family ID | 41818705 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239742 |
Kind Code |
A1 |
Muller; Ralf ; et
al. |
October 6, 2011 |
APPARATUS FOR TREATING A MEDICAL LIQUID, AND METHOD FOR CHECKING
THE LEAKTIGHTNESS OF THE APPARATUS
Abstract
The invention relates to an apparatus for treating a medical
liquid which includes a treatment machine having a coupling surface
and a flexible mat arranged on the coupling surface, with a
cassette made of a hard part having liquid-conducting passages
which are covered by a flexible film being able to be coupled to
the coupling surface of the treatment machine via the flexible mat.
In accordance with the invention, the apparatus for making possible
the monitoring of a fault-free coupling to the cassette at the
coupling surface is made such that a pressure difference of the
pressure can be determined between the cassette and the flexible
mat and of the pressure between the mat and coupling surface. The
invention furthermore relates to a method for the checking of the
leak tightness of the aforesaid apparatus.
Inventors: |
Muller; Ralf; (Bad Homburg,
DE) ; Scheunert; Peter; (Friedrichsdorf, DE) ;
Gerlach; Daniel; (Frankfurt am Main, DE) |
Family ID: |
41818705 |
Appl. No.: |
13/133789 |
Filed: |
December 11, 2009 |
PCT Filed: |
December 11, 2009 |
PCT NO: |
PCT/EP09/08881 |
371 Date: |
June 9, 2011 |
Current U.S.
Class: |
73/49.2 ;
210/232 |
Current CPC
Class: |
A61M 2205/70 20130101;
A61M 1/14 20130101; A61M 2205/122 20130101; A61M 1/28 20130101 |
Class at
Publication: |
73/49.2 ;
210/232 |
International
Class: |
G01M 3/04 20060101
G01M003/04; B01D 35/30 20060101 B01D035/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2008 |
DE |
10 2008 062 037.8 |
Claims
1. An apparatus for the treatment of a medical liquid which
includes a treatment machine having a coupling surface and a
flexible mat arranged on the coupling surface, wherein a cassette
made from a hard part with liquid conducting passages which are
covered by a flexible film can be coupled to the coupling surface
of the treatment machine via the flexible mat, wherein the air
between the flexile film and the flexible mat can be removed via
suction openings in the cassette, characterized in that a
deflection of the flexible mat or of parts of the flexible mat can
be determined.
2. An apparatus in accordance with claim 1, characterized in that
the flexible mat is made more flexible at predetermined points than
in the other regions.
3. An apparatus in accordance with claim 1, characterized in that
the flexible mat is more flexible at predetermined points in that
it is made thinner than in the other regions.
4. An apparatus in accordance with claim 1, characterized in that
the flexible mat is encompassed by an annular groove at least one
predetermined point.
5. An apparatus in accordance with claim 1, characterized in that
the flexible mat is made in concave form or in convex form at least
one predetermined point with respect to the other points.
6. An apparatus in accordance with claim 1, characterized in that
the monitoring of the deflection of the more flexible region of the
flexible mat is carried out by a sensor.
7. An apparatus in accordance with claim 6, characterized in that
the sensor is a stylus.
8. An apparatus in accordance with claim 6, characterized in that
the sensor is a sensor working in a contactless manner.
9. An apparatus in accordance with claim 8, characterized in that
the sensor is an ultrasonic sensor, a capacitive sensor or a light
barrier.
10. An apparatus in accordance with claim 1, characterized in that
a pressure sensor or a force sensor serves as the sensor.
11. A method for the checking of the leak tightness of the
apparatus in accordance with claim 1 after the coupling of the
medical cassette to the coupling surface of the treatment machine
via a flexible mat arranged on the coupling surface and after or
during the suction of air between the flexible film and the
flexible mat during the coupling process and/or with a coupled
cassette, characterized in that the vacuum formed between the
flexible film and the coupling surface is checked by a comparison
of the pressure between the flexible mat and the film, on the one
hand, with the pressure between the flexible mat and the coupling
surface, on the other hand.
12. A method in accordance with claim 11, characterized in that,
before the coupling of the medical cassette, an initial check of
the measurement device takes place before the coupling of the
cassette by evacuation of the intermediate space between the mat
and the coupling surface.
13. A method in accordance with claim 11, characterized in that the
deflection of the flexible mat or of parts of the flexible mat is
measured for the determination of the differential pressure.
Description
[0001] The invention relates to an apparatus for the treatment of a
medical liquid in accordance with the preamble of claim 1. The
invention furthermore relates to a method for checking the leak
tightness of the aforesaid apparatus.
[0002] A corresponding apparatus for the treatment of a medical
liquid can, by way of example, be a blood treatment machine such as
is used in hemodialysis or in peritoneal dialysis. In such a use,
the medical cassette includes the blood-conducting or dialysis
liquid-conducting passages and is in communication with actuators
and sensors of the treatment machine via the coupling surface. The
medical cassette can thus be configured as a cost-effective
disposable part, whereas the actuators for the control of the
liquid flow through the cassette and the sensors are integrated
into the treatment machine for the level detection or for the
pressure measurement.
[0003] Such medical cassettes configured as disposable articles
comprise in this connection a thin-walled three-dimensional hard
plastic part having a planar peripheral contact edge and various
recesses (chambers, webs and passages). Medical liquids such as
dialysate or blood can now be conducted in the chambers and
passages formed by these three-dimensional structures of the hard
plastic part. The contact plane of the cassette is closed in a
liquid tight manner by a flexible film, advantageously a polymer
film which is peripherally connected, in particular welded and/or
adhesively bonded, to the contact edge of the hard part. The
medical cassette is pressed onto the coupling surface of the
treatment machine in use with the flexible film so that actuators
and sensors of the treatment machine lie on the polymer film. In
addition, the flexible film is pressed together with the webs of
the cassette by this pressing and thus provides a fluid tight
separation of the liquid-conducting passages in the hard part by
the webs and the flexible film.
[0004] Furthermore, the cassette passages can also be welded or
adhesively bonded to the flexible film to achieve a fluid-tight
separation of the liquid-conducting passages.
[0005] The coupling surface of the treatment machine accordingly
usually has actuators, sensors and pressing force transmission
surfaces. The actuators and sensors of the blood treatment machine
are arranged in this context in the coupled state of the cassette
opposite the liquid-conducting passages of the cassette. The
actuators can hereby form valves by the pressing down of the film
in that the flexible film is pressed into regions of the
liquid-conducting passages and closes them. The sensors, for
example, measure the pressure or temperature of the liquid located
in the liquid-conducting passages. In an embodiment of the
cassette, the pressing force transmission surfaces can press the
flexible film against sealing webs of the hard part which surround
the liquid-conducting passages to seal them with respect to one
another and with respect to the rest of the cassette.
Alternatively, the cassette passages can also be welded or
adhesively bonded. The coupling surface is usually formed by a
planar surface of a support member which is made e.g. from metal,
with receivers for the sensors and the actuators being provided in
said surface, and by the sensors inserted into these receivers in
planar fashion.
[0006] A flexible mat, made, for example, of silicone or another
elastomeric material, is usually arranged on the coupling surface
of the treatment machine. This has the advantage that the sensor
surfaces are protected against environmental influences and the
machine surface is moreover liquid tight and thus ideally
hygienically cleanable. The flexible mat in this context represents
a part of the treatment machine to which the cassette is coupled as
a disposable part. The operation of the actuators is ensured by the
flexibility of the mat. In addition, the flexible film can be
pressed well to the coupling surface via the flexible mat, whereby
a good contact with the actuators, sensors and pressing force
transmission surfaces is made possible.
[0007] On the coupling of the sensors to the film surface, there is
the difficulty with known surfaces of achieving a good coupling to
obtain correct measured values. In particular air which is trapped
in the transmission path between the flexible film and the sensor
surface on the insertion of the cassettes produces a falsification
of the measured results. This applies to pressure sensors (in
particular on the measurement of pressures which are less than the
environmental pressure), but also in level detection and likewise
to actuators such as valves. Unwanted air enclosures between the
outer surface of the flexible film and the mat surface of the
flexible mat lying thereon should therefore be eliminated on the
coupling. This usually takes place by air suction.
[0008] It is already known from DE 101 57 924 C1 and DE 102 24 750
A1 to realize the air transport by means of integrated mat
passages, predetermined in a defined manner, on the rear side of
the machine mat at the machine side. The air line from the surface
of the flexible film through the mat to the air passages arranged
on the machine side takes place locally through uninterrupted slots
in the region of the mat passages. The air transport however,
hereby only takes place at precisely defined points of the flexible
film of the cassette at which the air is sucked off through the
slots in the mat to the mat passages arranged on the machine side.
These mat passages therefore have to be located in the region of
the liquid-conducting passages of the cassette to ensure a good
suction there, which can lead to safety problems. In this
embodiment, the sensor surface is no longer ideally protected from
environmental influences and is not necessarily hermetically sealed
by the mat so that hygienic problems can, for example, occur.
[0009] To improve the reliable air suction and for the reliable
prevention of air islands, an apparatus for the treatment of a
medical liquid is proposed in DE 10 2007 042 964 A1 in which a
layer of an air-permeable porous material is arranged between the
flexile film and the coupling surface in the coupled state, with
air being able to be sucked out areally through said layer during
the coupling process and/or with a coupled cassette.
[0010] To satisfy the hygienic demands, it is necessary to
manufacture a closed, liquid-tight surface without sealing points,
joints or material transitions. The previously mentioned
uninterrupted flexible mat, which is made of silicone rubber,
serves exactly this purpose. It separates the sensors and actuators
from the cassette film. Two regions which have to be evacuated for
the coupling of the cassette result on the basis of this
separation, namely the region between the mat and the coupling
surface and, on the other hand, the region between the upper side
of the mat and the cassette film. Whereas the suction at the
machine side between the coupling surface and the mat side facing
it is solved for the sufficiently provided air conduction passages
in the aforesaid DE 10 2007 042 964 A, the coupling on the cassette
side is more complex and/or expensive on the cassette side due to
the high demands on the cleanability and due to the machine
surface.
[0011] If, for example, an intermediate space should arise between
the flexible mat and the cassette film due to air leakages from the
outside, this can result in the decoupling of the actuators and in
incorrect measurements of the sensors.
[0012] The reasons for a collapse of the vacuum between the
flexible mat and the film of the cassette lying thereon can be
insufficient sealing to the ambient air. A good air permeability
between the silicone mat and the film is required on the suction of
the cassette film. However, it must be interrupted in the marginal
region of the cassette.
[0013] A high demand is thereby made on the sealing tightness
between the film and the flexible mat so that comparatively high
pressure differences can be maintained. If leaks occur due to dirt,
damage, collapsed points or foreign bodies, the vacuum cannot be
maintained.
[0014] In known apparatus, a suction opening with a hydrophobic
membrane is provided for the suction of any air present between the
film and the flexible mat. The known systems are, however, very
prone to failures, with corresponding failures here not being able
to be detected with known apparatus. If, for example, a closure of
the hydrophobic membrane of the aforesaid suction opening arises
due to liquid, it cannot be detected by the machine whether the
intermediate space between the film and the flexible membrane was
actually evacuated. The suction can likewise be realized by an
opening in the mat 12. Leak detectors on the machine side can
thereby also recognize a liquid leak when a protective device with
a hydrophobic membrane is provided.
[0015] If, on the other hand, due to a kinking of the pneumatic
hoses in the machine, a closure of the hose occurs, the suction
process of the air from the intermediate space between the film ad
the flexible mat is interrupted.
[0016] A particularly critical case which can occur in an extreme
case consists of the fact that on damage to the film, blood, for
example, emerges from the cassette and fills the intermediate space
between the film and the flexible mat. It is here not just a
question of ensuring the coupling of the sensors and actuators to
the cassette, but rather also to avoid the blood loss and a
potential contamination of the patient's blood.
[0017] Generally, sufficiently good suction can be ensured by the
evacuation possibilities between the film and the flexible mat. In
this respect, not only the suction of air is possible, but rather
also that of liquids--such as blood. It can thereby be assumed on a
liquid leak, precisely as with a gas leak, that the penetrating
medium is conveyed up to the suction opening.
[0018] It is now the object of the present invention to further
develop a generic apparatus such that a monitoring of the exact
coupling between the coupling surface of the treatment machine
comprising a flexible mat, on the one hand, and the film covering
the cassette, on the other hand, is ensured in a simple manner.
[0019] This object is solved in accordance with the invention by an
apparatus for treating a medical liquid which includes a treatment
machine having a coupling surface and a flexible mat arranged on
the coupling surface, with a cassette made of a hard part having
liquid-conducting passages which are covered by a flexible film
being able to be coupled to the coupling surface of the treatment
machine via the flexible mat. The air present between the flexible
film and the flexible mat can be sucked out via suction openings in
the cassette. In an alternative embodiment, the air can also be
evacuated through openings in the mat. In a further embodiment, the
air is removed manually by clamping the cassette to the mat. In
this process, the air is pressed out between the cassette and the
mat by mechanical pressure (for example by a lever or a door seated
thereon). The flexible mat can now be made more flexible in the
region above the measurement device than in other regions to
facilitate a deflection there by pressure differences between the
pressure level at both sides of the flexible mat.
[0020] A suitable force sensor can also be used instead of a sensor
which monitors the deflection or elongation of the mat. On the use
of a corresponding force sensor, only negligible deflections of the
mat occur in the region of the measurement chamber. The sensor
namely captures the mat in the region of the measurement space and
monitors the force effect onto the mat in this region.
[0021] Special embodiments of the invention result from the
subordinate claims dependent on the main claim.
[0022] Accordingly, the flexible mat can be made more flexible
above the measurement device in that it is made thinner than in the
other regions. Due to the thinner embodiment of the mat which is
flexible per se, particularly the region above the measurement
device can be deflected further and its deflection can thus be
easily detected. Any differential pressure of the adjacent
evacuated spaces can hereby be monitored in a simple and secure
manner. Alternatively, the flexible mat can also be encompassed
above the measurement device by an annular groove which likewise
facilitates a deflection of the mat in the region above the
measurement device.
[0023] The monitoring of the deflection of the region of the
flexible mat above the measurement device is advantageously carried
out by a sensor.
[0024] The sensor can advantageously be a stylus or also a sensor
operating in a contactless manner such as an ultrasonic sensor, a
capacitive sensor or also a light barrier. The sensor can equally
be a force sensor or a pressure sensor or similar. These sensors
provide the advantage that only negligibly small deflections of the
mat above the measurement device are necessary for the detection of
the pressure difference between the adjacent evacuated spaces.
[0025] A method in accordance with the invention for the checking
of the leak tightness of the apparatus in accordance with one of
the preceding claims according to the steps: [0026] Initial
checking of the measurement device before the coupling of the
cassette by evacuation of the intermediate space between the mat
and the coupling surface; [0027] Coupling the medical cassette to
the coupling surface of the treatment machine via a flexible mat
arranged on the coupling surface; and [0028] Suction of air between
the flexible film and the flexible mat during the coupling process
and/or with a coupled cassette consists of the fact that the vacuum
formed between the flexible film and the coupling surface is
checked by a comparison of the pressure between the flexible mat
and the film, on the one hand, with the pressure between the
flexible mat and the coupling surface, on the other hand.
[0029] The first step of the aforesaid method sequence relates to
the initial check of the measurement device. This initial check is
a test of the sensor apparatus before the coupling of the cassette.
The air between the mat and the coupling surface is evacuated here.
This is done through a suction opening in the coupling surface.
Corresponding suction passages provide a full-area evacuation of
the air between the coupling surface and the mat. With a flexible
embodiment, the mat moves in the direction of the sensor which
monitors the elongation of the mat due to the pressure gradients
which hereby arise between the sensor space and the outside air.
Alternatively, on the use of a force sensor, a force here acts on
the alternatively provided force sensor. A corresponding signal
must therefore be recognized during the self-test to be able to
confirm the problem-free function of the measurement device.
[0030] The deflection of the flexible mat above a sensor is
measured for the determination of the differential pressure.
[0031] Further features, details and advantages of the invention
will be explained with reference to an embodiment shown in the
drawing. There are shown:
[0032] FIG. 1: the principle structure of a cassette coupled to a
treatment machine in partial section in accordance with the prior
art;
[0033] FIG. 2: an embodiment of the apparatus made in accordance
with the invention for the treatment of the medical liquid in a
first working position; and
[0034] FIG. 3: the apparatus in accordance with FIG. 2 in a second
working position.
[0035] FIG. 1 shows an apparatus for treating a medical liquid such
as is used in the prior art, for example for hemodialysis or
peritoneal dialysis. Such apparatus can, however, also be used in a
plurality of other fields of application in which a disposable
cassette, which is also called a disposable, is used and is coupled
to sensors and actuators of a treatment machine via a coupling
surface.
[0036] The treatment surface 10 in this connection has a coupling
surface 12 and a flexible mat 14 arranged on the coupling surface
12. A cassette 18 encompasses a hard part 20 as well as a flexible
film 22; different blood passages 24, 26, 28 are defined by the
hard part 20 and/or the flexible film 22.
[0037] In accordance with the exemplary embodiment of the invention
shown in FIGS. 2 and 3, the monitoring of the vacuum between the
film 22 and the flexible mat 14 is now realized by a comparison of
the pressure on the machine side with the pressure between the
flexible mat 14 and the coupling surface 12 with the pressure
between the film 22 and the flexible mat 14. For this purpose, as
is shown in FIGS. 2 and 3, the region 36 of the flexible mat 14
above a sensor 42 is preferably made thinner than in its other
regions and is thereby made more flexible and more yielding. After
the initial test, the air between the flexible mat 14 and the
coupling surface 12 is evacuated. The part of the flexible mat
which is located above the sensor 42 is accordingly moved in the
direction of the sensor by the external pressure. With a correct
coupling of the cassette 18 to the mat 14, the air between the
cassette 18 and the mat 14 is evacuated. The pressure difference
between the pressures P1 in the space between the cassette 18 and
the mat 14 and P2 in the space between the mat 14 and the coupling
surface 12 is accordingly zero. No outer forces thus act onto the
partial piece 36 of the flexible mat above the sensor and the mat
adopts its previously flat shape in this region, as shown in FIG.
2.
[0038] In FIG. 3, the case is shown that the coupling of the
cassette 18 to the mat 14 has not taken place properly, that is,
the air between the cassette 18 and the mat 14 was not completely
removed. The pressure P1 in the space between the cassette 18 and
the mat 14 is thus larger than the pressure P2 in the space between
the mat 14 and the coupling surface 12, whereby the part pressure
36 of the flexible mat above the sensor remains arched in the
direction of the sensor.
[0039] The sensor 42 detects the deflection of the flexible mat
above the sensor in a suitable manner. This sensor can, for
example, comprise a contactless sensor such as an ultrasonic sensor
or a capacitive sensor. Instead of the sensor 42 shown here, a
reflected light barrier can, for example, also be used which is
completely covered in the region of the more flexibly designed
region 36 on the deflection of the flexible mat 14.
[0040] A flexible annular groove 44 is provided, as shown in FIGS.
2 and 3, for the improvement of the deflection of the region 36 of
the flexible mat 14 made thinner.
[0041] In an alternative embodiment, the partial piece 36 of the
flexible mat 14 is preshaped in the direction of the sensor 42. In
this respect, the situation results as shown in FIG. 3 without any
evacuation of the air between the flexible mat 14 and the coupling
surface 12. With a correct coupling of the cassette 18 to the mat
14, the air between the cassette 18 and the mat 14 is evacuated.
The pressure P1 in the space between the cassette 18 and the mat 14
is accordingly smaller than the pressure P2 in the space between
the mat 14 and the coupling surface. A force thus acts onto the
partial piece 36 of the flexible mat above the sensor away from the
sensor 42, whereby the partial piece 36 of the flexible mat 14 is
pressed toward the cassette 18, as shown in FIG. 2. The proper
coupling of the cassette 18 to the mat 14 is also monitored in this
embodiment by measurement of the deflection of the partial piece 36
of the flexible mat 14 by a suitable sensor.
[0042] If now, as shown in the example of FIG. 3, it is found that
the vacuum between the film 22 and the flexible mat 14 was not
maintained, a previously determined measure can be initiated such
as the ending of the treatment to guard against a risk to the
patient. For this purpose, the signal of the sensor 42 is forwarded
in a previously unknown manner via the line 46 to a control device
not shown in any more detail here and in which, after the arrival
of the corresponding signal, suitable measures were taken to
terminate the treatment.
* * * * *